Please log in

or

Register now for free

or

Choose your profile *

Email *

A valid e-mail address. All e-mails from the system will be sent to this address. The e-mail address is not made public and will only be used if you wish to receive a new password or wish to receive certain news or notifications by e-mail.

Password

Username *

Sign up to our newsletters

Higher education updates from the THE editorial team

World University Rankings news

Student newsletters

Send me special offers and marketing info from THE and selected partners

ESA satellite images assist US emergency services

The European Space Agency (ESA) is contributing to Hurricane Katrina alert and rescue efforts in the
US, providing images and data captured by its satellites.

The International Charter on Space and Major Disasters was activated on August by the US Geological
Service. ESA is a founding member of the Charter, which stipulates that global space agencies will put
their resources at the service of rescue authorities facing major natural or man-made disasters. The
Charter has already been activated more than 80 times since it was signed in 2000.

ESA's Envisat satellite captured images of Hurricane Katrina as it moved from the Gulf of Mexico into
the US. Further ESA images and data will also be made available.

An optical image from Envisat shows the spiralling cloud patterns expected in a hurricane. A radar
observation also pierces through the clouds to show how the hurricane's 250 km/hour winds scour the
sea's surface. Envisat gathered the images using its medium resolution imaging spectrometer (MERIS) and
advanced synthetic aperture radar (ASAR).

The ASAR instrument works by recording signal backscatter based on the sea's surface roughness. The
storm's centre, which is wind-free, appears as a dark ring measuring approximately 60 km across. It
shows up darker in the images because the water here is hardly rippled in comparison with the
surrounding sea.

Casualties have been reported in the Gulf coast area, but exact numbers are yet to be determined. Much
of New Orleans is currently underwater.

Hurricane Katrina formed in the Bahamas in mid-August, and struck South Florida on 25 August, killing
nine people and leaving around a million without electricity.